Method of managing copy protection information of a recording medium, recording medium with copy protection information for contents recorded thereon, and reproducing method for the recording medium

ABSTRACT

The present invention relates to a method of managing CPI (Copy Protection Information) for preventing unauthorized copy of encrypted content recorded on a high-density recording medium such as a BD-ROM (Blu-ray Disc ROM). In the present method, when main content data is recorded in encrypted manner, CPI that is necessary to decrypt the encrypted main content data is written in a predetermined PIC area and is also copied at least once in an area other than the PIC area.

1. TECHNICAL FIELD

The present invention relates to a method of managing copy protection information (CPI) for preventing an illegal copying of encrypted contents recorded on a high-density recording medium such as a BD-ROM (Blu-ray Disc ROM), a recording medium having the copy protection information stored thereon, and a method of reproducing the recording medium.

2. BACKGROUND ART

The standardization of new high-density optical disks capable of recording large amounts of high-quality video and audio data has been progressing rapidly and new optical disk related products are expected to be commercially available on the market in the near future. The Blu-ray Disc Rewritable (called ‘BD-RE’ in general) is one example of these new optical disks.

As shown in FIG. 1, a BD-RE disk comprises a clamping area, a transition, area, a burst cutting area (BCA), a lead-in area, a data area, and a lead-out area in order starting from the innermost circumference.

The lead-in area comprises several pre-assigned areas such as a first guard (Guard 1) area, a permanent information & control data (PIC) area, a second guard (Guard 2) area, a second information (Info 2) area, and an optimum power calibration (OPC) area. The Guard 1 area and the PIC area are pre-recorded areas in which some initial data is pre-recorded, whereas the other areas of the lead-in area, the data area, and the lead-out areas are all rewritable areas.

In the PIC area, important information about the disk, which is to be preserved permanently, is encoded in a wobbled groove by high frequency modulation (HFM). As shown in FIG. 2, the wobble-shaped data encoding is performed by bi-phase modulation.

In the mean time, the development of the read-only Blu-ray disk (BD-ROM) is also under way along with the development of the BD-RE. A BD-ROM disk comprises an inner area, a clamping area, a transition area, an information area, and a rim area, as shown in FIG. 3.

The contents of A/V streams are recorded in the data zone belonging to the information area in an encrypted manner using the copy protection information (CPI) with a view to preventing an illegal copying of the contents.

Disc information (DI) such as disc type is recorded in the PIC area belonging to the information area. In the case where the main data recorded in the data zone is encrypted, copy protection information (CPI) for decrypting the encrypted data is also recorded in the PIC area.

When an optical disk (a BD-ROM disk) is loaded into an optical disk reproducing apparatus, the optical disk reproducing apparatus first detects the copy protection information (CPI) recorded in the PIC area and then decrypts the main data recorded in the data zone using the copy protection information (CPI) if the main data is encrypted.

If an error occurs when the apparatus detects the copy protection information (CPI), which is required to decrypt the encrypted data, the contents of the BD-ROM disk cannot be decoded even if there in no data read error.

3. DISCLOSURE OF THE INVENTION

It is one object of the invention to provide a method of recording copy protection information on a recording medium that allows reliable read-out of the copy protection information for decrypting contents recorded on thereon.

It is another object of the present invention to provide a recoding medium having copy protection information for decrypting encrypted contents recorded thereon.

It is still another object of the present invention to provide a method of reproducing and decrypting encrypted contents recorded on a recording medium by using copy protection information recorded thereon.

A method of recording copy protection information on a recording medium in accordance with the present invention comprises recording encrypted data on the recording medium, and recording the copy protection information required for decrypting the encrypted data in a predetermined first area and additionally in an area other than the first area at least once.

A recording medium in accordance with the present invention comprises a data area storing encrypted data, a first area storing copy protection information required for decrypting the encrypted data, and at least one second area storing a duplicate of the copy protection information.

A method of reproducing a recording medium by a disk reproducing apparatus in accordance with the present invention comprises the steps of (a) driving the recording medium storing encrypted data, (b) detecting copy protection information, which is required for decrypting the encrypted data, recorded in a first area of the recording medium, and (c) if an error occurs in the detection of the copy protection information, detecting duplicated copy protection information from an area other than the first area and decrypting the encrypted data using the detected copy protection information.

The method of recording and reproducing the copy protection information of a recording medium in accordance with the present invention allows encrypted data recorded on the recording medium to be reproduced normally even when the copy protection information cannot be read from the PIC area in which the copy protection information is supposed to be recorded, due to scratches, finger prints, etc.

4. BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 illustrates the structure of a BD-RE disk;

FIG. 2 illustrates a high-frequency modulated (HFM) groove formed in the PIC area of the BD-RE disk;

FIG. 3 illustrates areas assigned in a BD-ROM disk;

FIG. 4 illustrates disk information (DI) and copy protection information (CPI) recorded in the PIC area of the BD-ROM disk;

FIG. 5 shows an example in which the copy protection information (CPI) is written more than twice in accordance with the present invention;

FIG. 6 illustrates the structure of the disk information table including a duplicate of the copy protection information (CPI) in accordance with the present invention;

FIG. 7 illustrates a brief block diagram of an optical disk reproducing apparatus in which the present invention may be advantageously embodied; and

FIG. 8 illustrates an embodiment of a method of reproducing a recording medium in accordance with the present invention.

5. BEST MODE FOR CARRYING OUT THE INVENTION

In order that the invention may be fully understood, preferred embodiments thereof will now be described with reference to the accompanying drawings.

A BD-ROM disk in accordance with the invention has a disk structure comprising an inner area, a clamping area, a transition area, an information area, and a rim area, as shown in FIG. 3.

The data zone assigned in the information area stores moving picture contents such as movies. As shown in FIG. 4, the PIC area assigned in the data zone stores the disk information, which is general information about the disk, and the copy protection information (CPI), which is required to decrypt contents recorded in the data zone in an encrypted manner. In case of a BD-ROM disk, the data recording is conducted by forming pre-pits on the surface of the BD-ROM disk.

The disk information and CPI stored in the PIC area is recorded as straight pits, or wobbled pits, or partly as wobbled pits and partly as straight pits.

The CPI stored in the PIC area, which is a key value used to encrypt the main data recorded in the data zone, is duplicated at least once in areas other than the PIC area.

FIG. 5 shows an example in which the CPI is written additionally in areas other than the PIC area.

In FIG. 5, the duplicated CPI is found in a reserved area of the lead-in area and in a reserved area of the lead-out area. In FIG. 5, the disk information as well as the CPI is duplicated in these areas.

The CPI may be duplicated at least once only in the lead-in area, at least once only in the lead-out area, or at least once both in-the lead-in area and in the lead-out area.

The areas on a BD-ROM in which the CPI is to be duplicated may be specified by the BD-ROM standard or may vary depending on manufacturers. In the latter case, information on the position of each duplicated CPI is included in the disk information table.

FIG. 6 shows the structure of the disk information table in accordance with the present invention. The disk information table includes various types of information on the disk, including a disk information identifier, disk size/version, and disk structure. In addition, the disk information table includes information on respective duplicated CPI positions. (CPI_position) in a reserved field.

The size of the position information (CPI_position) is proportional to the number of the duplicated CPIs. If information on the position of each duplicated CPI is assigned 4 bytes and there are N duplicated CPIs, the size of the position information (CPI_position) is 4×N bytes.

In the case where the disk information is duplicated along with the CPI in the lead-in area and/or lead-out area, the information on the respective CPI positions is also duplicated.

FIG. 7 illustrates a brief block diagram of an optical disk reproducing apparatus in which the present invention may be advantageously embodied. The apparatus, which comprises an optical pickup 11 for reading optical information from a BD-ROM disk, a VDP (video disc play) system 12 for signal processing and servo control, and a D/A converter 13, decrypts the contents recorded on the BD-ROM disk using the copy protection information and outputs A/V signals by following a procedure illustrated in FIG. 8.

If a BD-ROM disk having copy protection information stored thereon is inserted into the apparatus (S10), the VDP system 12 rotates the BD-ROM and controls the optical pickup 11 to search the PIC area of the BD-ROM for the CPI and disk information (S11)

If an error occurs when reading the CPI (S12), the VDP system 12 checks if there is an error in the disk information (S13). If no error is found (S13-1), the VDP system 12 reads information on duplicated CPI positions (CPI_position) recorded in the disk information (S14) and then reads the CPI by moving the optical pickup 11 to a position where a duplicated CPI is written (S15). If a read error occurs again, the VDP system 12 moves the optical pickup 11 to a next position where a duplicated CPI is written and reads the CPI recorded therein (S16).

If the disk information read from the PIC area has an error (S13-1), the optical disk reproducing apparatus reads information on the position of CPI and/or disk information stored in a predetermined position of the apparatus (S20) and reads the CPI by moving the optical pickup 11 to the position (S21).

If the CPI is detected normally, the VDP system 12 moves the optical pickup 11 to the data zone from which to begin reproducing encrypted contents and decrypts the reproduced contents using the CPI (S17). And the VDP system 12 decodes the decrypted contents and finally outputs A/V signals (S18).

The described method of recording and reproducing the copy protection information for a recording medium allows encrypted data recorded on the recording medium to be reproduced normally even when the copy protection information cannot be read from the PIC area due to scratches, finger prints, etc.

While the invention has been disclosed with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations therefrom. It is intended that all such modifications and variations fall within the spirit and scope of the invention. 

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 19. A method of recording data on a recording medium, comprising: (a) generating a control information unit to control a recording or reproducing of data, wherein the control information unit includes an identifier to indicate where a copy protection information is recorded, the copy protection information is required for generating and/or processing a copy-protected data; and (b) recording the control information unit at a specific area of the recording medium.
 20. The method of claim 19, further comprising: (c) recording the copy-protected data in a main data area of the recording medium.
 21. The method of claim 19, wherein the specific area is a zone within a lead-in area or a lead-out area defined in the recording medium.
 22. The method of claim 19, further comprising: (d) recording the copy protection information in the recording medium.
 23. The method of claim 22, wherein the step (d) records the copy protection information in a zone other than a specific zone within a lead-in area where the control information unit is recorded.
 24. The method of claim 23, wherein the step (d) records the copy protection information copied from original copy protection information pre-recorded on the recording medium.
 25. The method of claim 24, wherein in the step (a) the identifier indicates a position where the copied copy protection information is recorded.
 26. The method of claim 22, wherein the copy protection information includes a key value required for generating/processing the copy-protected data.
 27. The method of claim 19, wherein the recording medium is an optical disc, the step (a) generates the control information unit including a disc information containing at least disc type information, disc size information, disc structure information, and data zone allocation information.
 28. The method of claim 27, wherein the step (a) generates the control information unit copied from original control information unit pre-recorded in the recording medium, while the copy protection information is information copied from original copy protection information pre-recorded in the recording medium, wherein the identifier included in the copied control information unit indicates at least a specific zone where the copied copy protection information is recorded.
 29. A recording medium, comprising: a control data area including a control information unit to control a recording or reproducing of data, wherein the control information unit includes an identifier to indicate where a copy protection information is recorded, the copy protection information is required for generating and/or processing a copy-protected data; and a main data area where data is recorded or to be recorded.
 30. The recording medium of claim 29, wherein the main data area includes the copy-protected data generated by the copy protection information.
 31. The recording medium of claim 29, wherein the copy protection information is recorded in a zone other than a specific zone within the control data area where the control information unit is recorded.
 32. The recording medium of claim 31, wherein the copy protection information is a copied information from original copy protection information pre-recorded on the recording medium.
 33. The recording medium of claim 32, wherein the identifier indicates a zone where the copied copy protection information is recorded.
 34. The recording medium of claim 29, wherein the control data area is a lead-in area or a lead-out area defined in the recording medium.
 35. The recording medium of claim 34, wherein the control data area is divided into a zone where the copy protection information is recorded and other zone where the control information unit is recorded.
 36. The recording medium of claim 29, wherein the recording medium is an optical disc, the control information unit includes a disc information containing at least disc type information, disc size information, disc structure information, and data zone allocation information.
 37. The recording medium of claim 36, wherein the control information unit is information unit copied from original control information unit pre-recorded in the recording medium, while the copy protection information is information copied from original copy protection information pre-recorded in the recording medium, wherein the identifier included in the copied control information unit indicates at least a specific area where the copied copy protection information is recorded.
 38. The recording medium of claim 29, wherein the copy protection information includes a key value required for generating/processing the copy-protected data.
 39. The recording medium of claim 38, wherein the key value is recorded in wobbled form and/or straight pre-pit form. 